Screen flipping out, typing by itself
My son dropped his iPad mini cracking the screen. The iPad still worked fine, he used it that way for a month. It then started typing and changing apps by itself and just flipping out. I assumed it was because the screen was cracked so I got a new digitizer from ifixit. I replaced it carefully using the repair guide. When I powered it back up everything worked fine for a while, then It started doing the same thing again. There seems to be no rhyme or reason why. It will work fine for 20 minutes, then start doing it even if is not being touched. If I power it down then turn it back on, it will work fine for a while, then do it again. Do I need to open it back up and check my work or do you have any other suggestions. Thanks.